Apparatus for positioning a search unit



mmmm (39 3 93719524- X f i. I?

March 5, 1968 J. T. WLOSZEK 3,371,524

' APPARATUS FOR POSITIONING A smncn UNIT Filed Oct. 15, 1964 6Sheets-Sheet l INVENTOR. JOSEPH T. WLOSZEK ATTORNEYS March 5, 1968 J. T.WLOSZEK 3,371,524

APPARATUS FOR POSITIONING A SEARCH UNIT Filed Oct. 15, 1964 6Sheets-Sheet 2 FIG. 2

(PRIOR ART) 2 l6 A/w FIG.3

(PRIOR ART) H I INVENTOR. JOSEPH T. WLOSZEK ATTORNEYS March 5, 1968 J.T. WLOSZEK 3,371,524

APPARATUS FOR POSITIONING A SEARCH UNIT- Filed Oct. 15, 1964 6Sheets-Sheet 5 INVENTOR. JOSEP T. WLOSZEK MM & (3 9 ATTORNEYS March 5,1968 J. T. WLOSZEK 3,371,524

APPARATUS FOR POSITIONING A SEARCH UNIT Filed Oct. 15, 1964 6Sheets-Sheet 4 I02 FIG. 7

INVENTOR. JOSEPH T. WLOSZEK Liz? 7 ATTORNEYS March 5, 1968 wLoszg3,371,524

APPARATUS FOR POSITIONING A SEARCH UNIT Filed Oct. 15, 1964 6Sheets-Sheet 5 99 WIIII'" INVENTOR. JOSEPH T. WLOSZEK BY7nzz &

ATTORNEYS March 5, 1968 J. T. WLOSZEK 3,371,524

APPARATUS FOR POSITIONING A SEARCH UNIT Filed Oct. 15, 1964 6Sheets-Sheet e FIG. 9

INVENTOR. JOSEPH T. WLOSZEK ATTORNEYS United States Patent f 3,371,524APPARATUS FOR PUSKTIONING A SEARCH UNIT Joseph T. Wloszek, Seven Hills,Ohio Custom Machine, Inc., 9200 George Ave., Cleveland, Ohio Filed Oct.15, 1964, Ser. No. 404,128 5 Claims. (Cl. 7367.8)

ABSTRACT OF THE DISCLOSURE Apparatus for positioning a nondestructiveultrasonic search unit, such as a liquid filled, flexible wheelcontaining a sound transducer, with respect to a workpiece. Structure isprovided for pivoting the wheel in two mutually perpendicular planesabout a pivot point located substantially at the point of contactbetween the wheel and a workpiece. Structure is also provided forcalibrating the search unit against a calibration piece, which isnormally located in a retracted position remote from the search unitwhile the search unit is inspecting a workpiece.

This invention relates to the art of nondestructive testing and moreparticularly to apparatus for positioning a nondestructive search unit.

The invention is particularly adapted for positioning the effective axisof a nondestructive search unit, such as an ultrasonic search unit, in adesired manner with respect to a workpiece being searched for flaws,internal or surface discontinuities, etc., and will be described withparticular reference thereto although it will be appreciated that theinvention has broader applications.

Search units utilized in nondestructive ultrasonic inspection may takeseveral forms and, for example, may be cylindrical in shape, coaxiallysurrounding a disk shaped transducer or may be a liquid filled flexiblewheel containing a disk shaped transducer. In either case, the effective axis of the transducer, i.e., the direction of transmitted soundpulses, may not be in exact alignment with the apparent search axis ofthe search unit as determined by the search units geometricalconfiguration. Further, even if the effective search axis is inalignment with the apparent or geometrical search axis, it may bedesirable -in certain applications to direct the sound pulses in adirection to obtain a desired propagation angle. The propagation angleis the angle defined by the intersection of the eifective axis of thetransducer and the entrant surface of the workpiece. Accordingly, it isdesirable that means he provided for positioning the search unitrelative to the entrant surface of the workpiece to obtain a desiredpropagation angle.

Heretofore in the art of nondestructive testing with the use ofultrasonic search units, adjustments of the propagation angle have beenobtained by pivoting the search unit about a point where the search unitis supported by a suitable support mount. However, by so pivoting thesearch unit the effective search axis will be directed at a point spacedfrom the desired area to be inspected and carriage means are required tomove the search unit later-ally so that the effective search axis willagain be directed at the desired area.

The present invention is directed toward a search unit mounting meansfor adjusting the propagation angle by pivoting the effective searchaxis of the search unit about a point located substantially on theentrant surface of the workpiece. In this manner, the need fordisplacing the pivot point according to such prior art search unitpositioning means, described hereinabove is effectively eliminated.

Patented Mar. 5, 1968 In accordance with the present invention there isprovided an apparatus for supporting and positioning a search unit toobtain a desired relationship between the effective search axis of theunit and-a workpiece being inspected. The apparatus includes supportingmeans for supporting the search unit with one end being adapted to bepositioned facing the entrant surface of the workpiece. Positioningmeans are provided for pivoting the search unit about a pointsubstantially on the surface of the workpiece. The positioning meansmay, for example, take the form of a pair of relatively movablecylindrical segments with the axes of cylindrical symmetry of the twocylindrical segments being perpendicular to each other and intersectingat the pivot point.

In accordance with a still further aspect of the present invention, anapparatus for supporting and positioning a search unit is provided forthe inspection of workpieces of annular cross-section, such as cylindersand spheres of different diameters in such a manner that the effectivesearch axis of the unit is always radially aligned with the workpiecebeing inspected. This apparatus includes movable support means forsupporting the search unit with one end thereof adapted to be positionedin contact with the outer surface of the workpiece. Further, stationarysupporting means are provided for supporting the workpieces of variousdiameters one at a time so that the centers of the workpieces define aplane. The movable supporting means is pivoted about a point which is solocated with respect to the plane as well as the effective axis of thesearch unit, that the elfective axis will always be in radial alignmentwith each of the workpieces taken one at a time when the search unit isin contact with the outer surface of the workpiece being inspected.

In accordance with another aspect of the present invention, means areprovided for protecting a flexible rotatable search wheel from damage bythe leading edge of a workpiece to be inspected by the search wheel. Theprotective means includes means for rotatably supporting a protectiveguide wheel with its plane of rotation parallel to the plane of rotationof the flexible search wheel, and with the protective guide wheel beinglocated to one side of the search wheel with its periphery spacedslightly inward from the periphery of the flexible search wheel. In thismanner, the guide wheel serves to guide movement of the workpiecerelative to the search wheel so that only a slight portion of theperiphery of the search wheel is in the path of the relative movementbetween the search Wheel and the workpiece.

-In accordance with a still further aspect of the present invention,search unit calibration apparatus is provided for calibrating the search'unit and includes a calibration piece which is normally in a retractedposition remote from the search unit while the search unit is inspectinga workpiece. Means are provided for selectively positioning thecalibration piece in a retracted position and in a calibration position.Also, suitable positioning means are provided for positioning the searchunit either adjacent the workpiece or adjacent to the calibration piecewhen the latter is in its calibration position for purposes ofcalibrating the search unit.

The primary object of the present invention is to provide apparatus forsupporting and positioning a search unit in a desired relationship withrespect to a workpiece being inspected, which apparatus is simple inconstruction and economcal to manufacture.

Another object of the present invention is to provide apparatus forsupporting and positioning a search unit relative to a workpiece inwhich the need for displacing a support carriage is effectivelyeliminated.

A still further object of the present invention is to providecalibration means for calibrating a sensing unit in a simple and timesaving manner.

In accordance with a still further object of the present invention,means are provided for radially aligning the effective search axis of asearch unit with workpieces of annular cross-section and variousdiameters, taken one at a time, in a manner which is simple inconstruction and economical in manufacture.

In accordance with a still further aspect of the present invention,means are provided for protecting a search Wheel unit from damage by theleading edge of a workpiece to be inspected, which means is simple inconstruction and economical to manufacture.

The invention may take physical form in certain parts and arrangement ofparts, the preferred embodiment of which will be described in detail inthis specification and illustrated in the accompanying drawings whichform a part hereof and wherein:

FIGURE 1 is a perspective view illustrating one embodiment of theinvention for inspection of pipe weld joints;

FIGURE 2 is a schematic diagram illustrating a problem incurred whenusing an ultrasonic search unit for detecting a flaw in a workpiece whenthe effective axis of the transducer contained by the unit is notaligned with the apparent or geometrical axis of the unit;

FIGURE 3 is a schematic diagram illustrating the manner in which asearch unit may be positioned with respect to a workpiece with anapparatus known heretofore in the prior art for purposes of obtaining adesired propagation angle of the effective axis of the search unit;

FIGURE 4 is a schematic diagram illustrating apparatus according to thepresent invention by which a search unit is positioned with respect to aworkpiece to obtain a desired propagation angle of the effective axis ofthe search unit with respect to a workpiece;

FIGURE 5 is an elevational view partly in cross-section illustrating theapparatus according to one embodiment of the present invention forpositioning a search unit with respect to a workpiece;

FIGURE 6 is a sectional view taken along line 6-6 of FIGURE 5;

FIGURE 7 is a plan view similar to that of FIGURE 6, but of smaller sizeillustrating a pair of protective guide wheels;

FIGURE 8 is a schematic diagram of the invention illustrating a sensingunit in position for purposes of inspecting a workpiece and acalibration piece in its retracted position;

FIGURE 9 is a schematic diagram of the invention illustrating thecalibration piece in its calibration position and the sensing unit inposition for calibration; and,

FIGURE 10 is a schematic diagram of the invention illustrating themanner in which the effective axis of the sensing unit is alwaysradially aligned with workpieces of various diameters.

Referring now to the drawings in which the showings are for the purposesof illustrating one embodiment of the invention and not for limitingsame, FIGURES 2, 3 and 4, respectively, schematically illustrate aproblem posed in the use of sensing units similar to that utilized inthe present invention, the manner in which the problem has been solvedby prior art apparatus, and the manner in which the problem is solvedaccording to the present invention. FIGURES 2, 3 and 4 each discloses anultrasonic search unit taking the form of a conventional liquid filledflexible search wheel 10 rotatably supported by a suitable yoke 12secured in any suitable manner to a support mount 14. As is well knownin the art of nondestructive ultrasonic fiaw inspection, the liquidfilled wheel 10 operates on the immersion principle in which a beam ofhigh frequency sound is projected through the liquid path into aworkpiece 16 for purposes of locating internal or surfacediscontinuities, such as internal flaw 18. A transducer 20 is locatedwithin the liquid filled wheel 10 and is held in a fixed positionrelative to the entrant surface 22 of the workpiece 16 while the wheel10 rotates freely about its axis of rotation. A problem posed in the useof such a search unit is that the effective axis OA of the transducer,that is the direction of the transmitted sound pulses, may not be inexact alignment with the apparent search axis OB of the search unit asdetermined by its geometrical dimensions. During a particular inspectionit may be desirable that the propagation angle be where the propagationangle is the angle defined by the intersection of the effective axis ofthe search unit and the entrant surface of the workpiece. As seen inFIGURE 2, if a search unit 10 has a misalignment of its effective axisand its apparent or geometrical axis, a propagation angle of 90 will notbe obtained by directing the search unit so that its geometrical orapparent axis OB defines an angle 0,, equal to 90 with respect to theentrant surface 22 of a test workpiece 16. Instead, the true propagationangle 0, as defined by the effective axis OA and its intersection withthe entrant surface 22. will be less than 90. Accordingly, for thepropagation angle 9,, to equal 90 the search wheel 10 must berepositioned so that its effective axis 0A is displaced in a clockwisedirection, as viewed in FIGURE 2, by an angle equal to 0 where 0 =6 0 Inaccordance with the teachings of the prior art mechanisms forpositioning a search unit with respect to the entrant surface of aworkpiece, reference is made to F1- URE 3 in which the propagation angle(9 has been increased to 90 by pivoting both the wheel 10 and itssupport mount 14 about a pivot point P by an angle 0 in a clockwisedirection, as viewed in FIGURE 3. Pivot point P is located at a point ator behind the wheel mount 14. By so pivoting the search wheel 10 the neweffective axis OA is located by a distance S in the downward direction,as viewed in FIGURE 3, from the flaw 18 in the workpiece 16, which wasto be detected. Accordingly, in order to maintain the propagation angle6,, equal to 90, but yet position the effective axis O'A at the locationof effective axis 0A in FIGURE 3 then suitable carriage means must beprovided for purposes of displacing both the wheel 10 and its mount 14in a vertical direction, as indicated by the arrow V, for a distanceequal to the distance S. Further, due to the pivotal move ment of wheel10 about pivot point P the periphery of the wheel may be displaced fromthe entrant surface 22 a slight distance in a direction away from theentrant surface. Accordingly, means must be provided for repositioningthe wheel 10 and its mount 14 by an equal dis tance in a directiontoward the entrant surface 22, as indicated by the arrow H, in orderthat the periphery of the wheel be in contact with the entrant surfaceof workpiece 16.

In accordance with the present invention means to be describedhereinafter are provided for pivoting the search wheel 10 about a pivotpoint P substantially located on the entrant surface 22 of the workpiece16 at the point of contact of the Wheel 10 and the entrant surface. Inthis manner it is seen that by pivoting the Wheel 10 and its mount 14about the pivot point P in a clockwise direction by an angle 0 as viewedin FIGURE 4, a propagaticn angle 0,, equal to 90 may be obtained. Theeffective axis CA has not been materially displaced as is the case withsuch prior art means as discussed with reference to FIGURE 3.Accordingly, the need for repositioning the search wheel in thedirections indicated by the arrows V and H in FIGURE 3, is effectivelyeliminated by the present invention when positioning the search wheel 10so that its enective axis 0A is directed at the flaw 18 in the workpiece16.

Although the description given heretofore has been with respect toangularly positioning a search wheel 20 in a vertical plane, i.e., theplane of the paper, it is to be appreciated that the discussion isequally applicable with respect to positioning the search wheel in aplane perpendicular to that of the paper. The description which followsis directed toward the means according to the present invention forangularly positioning the search wheel relative to a workpiece 16 ineach of two mutually perpendicular intersecting planes.

Referring now to FIGURES 1, 5, 6, 7 and 8, there is illustratedapparatus for supporting and positioning the search wheel 10 inaccordance with the present invention so that the periphery of the wheelis in contact with a workpiece area being inspected taking the form of aweld joint 24 extending longitudinally of a pipe 26, which is annular incross-section, as illustrated in FIGURE 5. The pipe 26 is supported forrelative movement with respect to the search Wheel 10 by means of aguide roller 28 suitably mounted for free rotation about its axis ofrotation. The yoke 12 which rotatably supports the search wheel 10 issecured to a supporting and positioning apparatus 30, one embodimentonly being illustrated in the drawings for purposes of illustrating theinvention and not for limiting same.

The supporting and positioning apparatus 30 includes an innercylindrical segment 32 with its outer surface 34 taking the form of acylindrical surface having a radius of curvature equal to the distancefrom surface 34 to the pivot point P located at the point of contact ofthe periphery of search wheel 10 and the workpiece 26. The axis ofcylindrical symmetry of surface 34 extends perpendicular to the plane ofthe paper of FIGURE 5 through the pivot point P The inner surface 36 ofthe cylindrical segment 32 is flat and parallel to the axis of symmetryof surface 34. Suitable fastening means, such as bolts 38, serve tosecure 2. depending mounting flange 40 of the yoke 12 to the innercylindrical segment 32. A suitable stud 42 is secured, such as by apress fit, or threaded at one end to the inner cylindrical segment 32 sothat the axis of the stud is perpendicular to the flat surface 36 andbisects segment 32 in the plane of the paper of FIGURE 5. Thecylindrical segment 32 terminates in opposite directions from stud 42 instop surfaces 44 and 46, each extending radially of the cylindricalsurface 34 of segment 32 and spaced equally from the axis of the stud42.

The supporting and positioning apparatus 30 is also provided with anouter cylindrical segment 48, having an outer surface 50 taking the formof a cylindrical surface having a radius of curvature equal to thedistance from the pivot point P to the surface 50. The cylindrical axisof symmetry of surface 50 is contained within the plane of the paper ofFIGURE 5 and extends through pivot point P in a direction perpendicularto the axis of stud 42. The inner surface 52 of cylindrical segment 48is also of cylindrical curvature having a radius of curvature extendingfrom surface 52 to the pivot point P The axis of cylindrical symmetry ofthe cylindrical surface 52 is the same as the axis of symmetry for thecylindrical surface 34 and the radius of curvature of the surface 52 isessentially that of surface 34 so that the surfaces are complementaryand permit relative movement of segments 32 and 48. The axis of stud 42bisects segment 48 in the plane of the paper of FIGURE 5 and segment 48terminates in a pair of bracket mounting surfaces 54 and 56, eachextending radially of the cylindrical surface 52 toward the pivot pointP and each spaced equally from the axis of stud 42. The mountingsurfaces 54, 56 serve to receive L-shaped brackets 58, 60, respectively,which are secured to the segment 48 in any suitable manner, such as bycountersunk bolts 62. The brackets 58, 66 are identical in shape andinclude depending flange portions 64 and 66, respectively, extendingtoward the pivot point P Adjust-ment bolts 68, 70 are respectivelythreaded through the depending flanges 64, 66 and extend generallyperpendicularly to the stop surfaces 44, 46, respectively. Adjustmentbolts 68, 70 have their ends 72, 74, respectively, maintained in contactwith the stop surfaces 44, 46 for purposes of angularly displacing thecylindrical segment 32 about pivot point 6 P as viewed in FIGURE 5. Theouter cylindrical segment 48 is provided with a circular slot 76 definedby radial wall 78 extending radially of the cylindrical surface 52 forlimiting the extent of angular displacement of inner cylindrical segment32 about the pivot point P The supporting and positioning apparatus 30is also provided with inner and outer end caps 82 and 84 which arespherical segments. The inner end cap 82 is provided with a sphericalouter surface 86 having its center of curvature at the pivot point P Theinner surface 88 of the inner end cap 82 is of cylindrical curvaturebeing a portion of a cylindrical surface having its radius of curvatureextending from points taken along the axis of symmetry of surface 50 tosurface 88. The cylindrical surfaces 50, 88 are complementary to permitrelative movement between segment 48 and inner end cap 82. The inner endcap 82 is also provided with :a radial wall 90 extending radially ofcylindrical surface 52 toward the pivot point P The radial wall 90 ispreferably an extension of the radial wall 76. The outer end cap 84 isprovided with an inner spherical surface 94 corresponding in curvatureessentially with that of the spherical surface 86 of the inner end cap82 so that a sliding fit is provided therebetween. The stud 42 extendsthrough the center of the spherical segment 84 and a suitable nut 96 isthreaded to the end of the stud 42 for purposes of clamping the outerend cap 84 to the inner end cap 82, as well as with the inner and outercylindrical segments 42 and 48.

The inner end cap 82 is provided with a depending annular flange 98which overlaps one side of an annular flange 100 of a support 102 and issecured thereto in any suitable manner, such as by bolts 104, so thatthe spherical end caps 82 and 84 extend through a circular aperture 106defined by the annular flange 100. A pair of depending side walls 108and 110 are provided on the support 102, each serving to threadablyreceive an adjustment bolt 112 and 114, respectively, as illustrated inFIG- URE 6. The outer cylindrical segment 48 terminates in the plane ofthe paper of FIGURE 6 in stop surfaces 116 and 118, respectively,extending radially of the cylindrical surface 59 of segment 48. Theadjustment bolts 112 and 114 extend through the side Walls 108 and 110in such a manner that their ends 120, 122 contact the stop surfaces 116,118, respectively.

In the operation of the supporting and positioning apparatus 30illustrated in FIGURES 5 and 6, the search wheel 10 may be pivoted aboutthe pivot point P for angular displacement in each of two mutuallyperpendicular planes which intersect at the pivot point P Thus, forexample, it may be desirable to pivot the search wheel 10 in the planeof the paper of FIGURE 5 about the pivot point P This is accomplished byloosening the nut 26 for purposes of releasing the clamping forceexerted between segment 34 and the outer cap 84. Thereafter, the innercylinder segment 32 to which the search Wheel 1i) and yoke 12 is securedmay be pivoted in the plane of the paper about the pivot point P bymerely tightening one of the adjustment bolts 68, 70 and loosening theother. That is, if it is desired to pivot the search Wheel 10 in acounterclockwise direction about the pivot point P as viewed in FIGURE5, then adjustment bolt 68 should be retracted with respect to stopsurface 64 of the inner segment 32 and the adjustment bolt 70 should beextended an equal amount in the direction toward stop surface 46 of thesegment 32.

Angular adjustment of the search wheel 10 about the pivot point P in theplane of the paper of FIGURE 6, may be obtained by loosening one of theadjustment bolts 112, 114 and tightening the other. Thus, for example,if it is desired that the search Wheel 16 be pivoted about the pivotpoint P in a counterclockwise direction, as viewed in FIGURE 6, thenbolt 112 should be retracted with respect to the stop surface 116 of theother cylindrical segment 48 and adjustment bolt 114 should be extendedan equal distance in the direction toward stop surface 118 of segment48. Upon completion of the adjustments of bolts 68, 7t and 112, 114, theadjustment is locked by tightening nut 96 so as to securely clamp theend caps 84, 82 and the segments 43, 32 tightly together.

Referring now to FIGURE 7, there is illustrated a pair of protectiveguide Wheels 557 and 99, respectively, located on opposite sides of theflexible search wheel Ill, and each being rotatably supported by meansof a support 101 which is in turn secured to the support plate 124. Thewheels 97 and 99 are preferably constructed of nonflexible material,such as metal, relative to that of wheel 1i). Each of the protectiveguide wheels 97, 99 has its plane of rotation parallel to that of theflexible wheel Iii and the rotational axis of wheels 1%, 97, 99 define aplane as evidenced by FIGURE 7. The diameter of the outer periphery ofthe wheel 97 is equal to that of the wheel 99, but less than that of thesearch wheel 10. Accordingly, with reference to FIGURE 7, it is seenthat the periphery of each of the wheels 97 and 99 in the area locatedadjacent workpiece 26 is spaced inwardly by a distance D from theworkpiece relative to the point of contact of the periphery of wheel andthe workpiece. In this manner the guide wheels 97 and 99 serve to guidemovement of the workpiece 26 relative to the search wheel It) so thatonly a slight portion of the periphery of the search wheel 19 is in thepath of relative movement between the search wheel and the workpiece.This protects the search wheel 10 from damage by the leading edge of theworkpiece.

Referring now to FIGURES 8 and 9, the supporting and positioningapparatus is illustrated in schematic form. The support 102 isillustrated in a simple manner with the yoke 12 secured thereto, andwith one end of the support being pivotally secured to a support plate124 for pivotal movement about a pivot post 126 perpendicular to theplane of the paper. The support plate 124 is pivoted about a pivot post130 for pivotal movement about a pivotal axis extending through the post1359 in a direction perpendicular to the plane of the paper. Pivotalmovement of the support plate 124 is accomplished by actuating asuitable hydraulic cylinder 132 pivoted at one end to a suitable pivotpost 134 and at the other end to a suitable pivot post 136 secured tothe support plate 124, in the manner illustrated in FIGURE 8. To theright in FIG- URE 8 there is schematically illustrated a calibrationunit 140 which serves the purpose of calibrating the search wheel 10against a calibration piece 142 having known flaws. The calibrationpiece 142 may take the form of a cylindrical pipe of annularcross-section, which is secured by means of a support 14-4- to a track146. The track 146 is in turn slidably secured to a track holder 143which serves to permit relative movement of track 146 together with thecalibration piece 142 in a direction perpendicular to the paper, thussimulating a workpiece passing by the periphery of the search wheel 16in the manner to be described hereinafter. The track holder 14-8 isprovided with an extended portion 150 which is pivotally secured to apivot post 152 for pivotal movement about a pivot axis extending throughthe post in a direction perpendicular to the plane of the paper. Pivotalmovement of portion d and, hence, of the calibration piece 142, isobtained by means of a suitable hydraulic cylinder 1S4 pivotally securedat its opposite ends to pivot posts 156, 158.

The calibration piece 142 is normally in its retracted position asillustrated in FIGURE 8 when the search wheel 10 is in position forinspecting flaws in the workpiece 25. However, when it is desired tocalibrate the search wheel It) against the calibration piece 142, thesupport plate 124 is pivotally displaced about pivot post 13% in aclockwise direction as viewed in FIGURE 8 to the position illustrated inFIGURE 9. The calibration piece I l-2 is pivoted about its pivot axis152 in a counterclockwise direction as viewed in FIGURE 8, by actuatingthe hydraulic cylinder 154 until the calibration piece 142 is in theposition illustrated in FIGURE 9 with the periphery of the search wheelIt) in contact with the calibration piece 142. This is the calibrationposition of the calibration piece 142.

With the search wheel lit and the calibration piece 142 in thecalibration position, the calibration piece 142 may be displaced bymeans of its track 146 and track holder 143 in the directionperpendicular to the plane of the paper for purposes of obtainingrelative movement of the calibration piece with respect to the wheel 16.After the desired calibrations have been accomplished hydrauliccylinders 154 and 132 may be suitably actuated to reposition thecalibration piece and the search wheel 10 to the positions illustratedin FIGURE 8.

Reference is now made to FIGURE 10 which schematically illustrates thesupporting and positioning apparatus 39 in a manner similar to that asillustrated in FIGURES 8 and 9, but without illustrating the calibrationunit 140. FIGURE 10 discloses structure by which according to thepresent invention the effective axis of the searchv wheel 19 ismaintained in radial alignment with objects of annular cross-sectionsupported one at a time regardless of their diameters. The support wheel28 supports roll stock, such as pipes and the like, of various diameterswhich are to be continually inspected for weld flaws as they pass thesearch wheel 10. The workpiece 26 illustrated in FIGURE 9 is illustratedby means of dotted lines in FIGURE 9 and has its axis of symmetryidentified by the character reference 26 A workpiece in the form of anannular pipe 27 is illustrated in FIGURE 10 supported by the supportwheel 28 and is a much larger diameter than that of the workpiece 26.However, it will be noted that the axis of symmetry 27 of pipe 27 andthe axis of symmetry 26 of the workpiece 26 define a plane AAperpendicular to the paper. Workpieces of annular cross-section, pipes26 and 27, of various diameters are supported by the wheel 28, which isso constructed that each workpiece will have its axis of symmetrylocated in the plane AA. Pivot point 126 of support 102 may itself bepivoted about pivot post by actuation of hydraulic cylinder 132. Withdistances Y and R held constant, pivot point 126 may be pivoted to alocation so that further pivotal movement of support 102 results inradial alignment of the effective axis 0A with either pipe 26 or pipe27. With the support plate 124 maintained in the angular relationship,as illustrated in FIGURE 10, the pivot point 126 of the support 102 isdisplaced a distance X from the plane AA. Also, when the effective axisOA of the search unit 10 is in radial alignment with the pipe 27, thedistance between the pivot point 126 and the effective axis 0A will beequal to the distance Y. Also, the pivot point P will be located adistance R from pivot post 126. In accordance with the present inventionthe distances Y and R are maintained constant. In this manner,regardless of the diameter of the workpiece being inspected radialalignment of the efiective axis 0A with respect to an annular workpiecewill be obtained.

Although the invention has been shown in connection with a preferredembodiment it will be readily apparent to those skilled in the art thatvarious changes in form and in arrangement of parts may be made to suitrequirements without departing from the spirit and scope of theinvention as defined by the appended claims.

I claim:

1. In an apparatus for inspection of workpieces including a search unitand positioning means for supporting and positioning said unit in adesired manner relative to an elongated workpiece being inspected as itmoves along a given path, the improvement comprising: sensing unitcalibrating apparatus including an elongated calibration piece extendingparallel to said given path and normally located in a retracted positionremote from said search unit while said search unit is inspecting a saidworkpiece,

said search unit positioning means and said sensing unit calibrationapparatus being both located transversely from and on fhdsiifieside'ofsaid given path, means for selectively pivoting said calibration pieceabout a pivot axis extending parallel to said given path between saidretracted position and a calibration position, and said search unitpositioning means having means for pivoting said search unit about asecond pivot axis extending parallel to said given path so that saidsearch unit contacts said calibration piece when the latter is in itscalibration position for purposes of calibrating said search unit.

2. An ultrasonic inspection apparatus including:

wheel mounting means;

a liquid ji lle d iigggibl e search wheel rotatably supported by saidmounting m aiis'j""said wheel containing a sound transducer fortransmitting sound pulses through the periphery of said wheel in adirection defining an elfective search axis extending transversely ofthe axis of rotation of said wheel;

means located exteriorly of said wheel for pivoting said wheel in twomutually perpendicular planes, of which one includes said axis ofrotation, and about a pivot point located substantially on the peripheryof said wheel;

said pivoting means including first and second relatively movablecylindrical segments;

said first cylindrical segment having an inner surface secured to saidwheel mounting means and a second cylindrical surface having an axis ofcylindrical symmetry extending through said pivot point;

said second cylindrical segment having an inner cylindrical surface inslideable contact with and of a curvature corresponding with the secondsurface of said first cylindrical segment, and an outer cylindricalsurface having an axis of cylindrical symmetry extending through said,pivot point and perpendicular to the axis of symmetry of said outersurface of said first cylindrical segment; and, a support for saidcylindrical segments having an inner cylindrical surface in contact withand of a curvature corresponding with the outer cylindrical surface ofsaid second cylindrical segments.

3. An apparatus as set forth in claim 2 including first adjustable meansinterposed between said first and second segments for displacing saidfirst segment with respect to said second segment so as to pivot saidwheel about the axis of cylindrical symmetry of said first segment.

4. An apparatus as set forth in claim 2 including means for securingsaid first and second segments for movement together about the axis ofsymmetry of said second segment.

5. An apparatus as set forth in claim 4 including supporting means forsaid wheel mounting means and said pivoting means, and second adjustablemeans interposed between said second segment and said supporting meansfor displacing both said first and second segments with respect to saidsupporting means so as to pivot said wheel about the axis of cylindricalsymmetry of said second segment.

References Cited UNITED STATES PATENTS 2,678,559 5/1954 Drake 73-67.82,836,059 5/ 1958 Beaujard et al 7367.8 2,940,305 6/1960 Williams et al7367.8 3,002,375 10/1961 Moffatt et al 7367.8 3,077,768 2/ 1963 Allardtet a1 7367.8 3,121,325 2/1964- Rankin et al. 7367.7 3,129,581 4/1964Bande 7367.8 3,257,843 6/ 1966 Cowan 73715 3,289,468 12/1966 Van derVeer et a1. 7371.5

JAMES J. GILL, Primary Examiner.

